Wings
XY-Wing
Three cells with pivot cell XY and two pincer cells XZ and YZ.
XYZ-Wing
Three cells with pivot cell XYZ and two pincer cells XZ and YZ.
WXYZ-Wing
Four cells with pivot cell WXYZ and three pincer cells WZ, XZ and YZ.
W-Wing
Four cells in a chain: a cell WX, a cell with X as a candidate, another cell with X as a candidate, another cell WX, such that the two cells containing X as a candidate have a strong link.

Simply stated a wing is a chain of 3. There are three strong links, at the beginning in the middle and at the end. Thay have names according to the pattern of whether the strong link is internal (a bivalue cell) or cell to cell (local).

XY-WING (x=y)-(y=z)-(z=x) any x that can see both ends can be eliminated.

ALS XY-WING is an xy-wing where one or more of the bivalue cells is replaced with a almost locked set (als)

W-WING (x=y)-y=y-(y=x) any x that can see both ends can be eliminated.

M-WING (x=y)-y=(y-x)=x any x that can see both ends can be eliminated.

Split wing S-WING x=y-(y=x)-x=y y may be eliminated from the beginning cell and x can be eliminated from the ending cell.

Local wing L-WING x=(x-z)=(z-y)=y y may be eliminated from the beginning cell and x can be eliminated from the ending cell.

Hybrid wing H-WING (x=y)-y=(y-z)=z x can be eliminated from the ending cell.

Hybrid wing H-WING (x=y)-(y=z)-z=z x can be eliminated from the ending cell.

XYZ-WING (x=y)-(y=xz)-(z=x) any x that can see both ends can be eliminated.

Exceptions:

X-WING is a fish pattern involving 2 rows and 2 columns.

WXYZ-WING two als's wxyz and wz one in a line the other in a box with the w's seeing each other. All other z's in both box and line that see all z's in als's can be removed.